This invention relates to containers in general, and more particularly relates to dispensing containers or cartridges for fluid products, having a slidable plunger for forcing the fluid contents of the cartridge out a dispensing aperture of a closure.
In the restaurant and food preparation industries, and particularly in the fast-food industry, thick or viscous fluid products such as condiments or sauces (e.g., ketchup, mustard, mayonnaise, dairy products, barbecue sauce, and the like) are often contained in tubular cartridges having one end closed by a closure that is formed separately from the cartridge body and is attached to the one end of the body. The closure defines one or more orifices through which the product can be dispensed. The cartridge is loaded into a manual dispensing device or “gun,” having a trigger that, when pulled, causes a plunger to be moved within the cartridge (similar to the operation of a caulking gun) and exert pressure on the product in the cartridge so as to force the product out through the one or more orifices in the closure. In this manner, the product can be rapidly dispensed into an individual-serving container or onto a food being prepared.
Various types of closures for such dispensing containers are known. The closure typically includes a metal end that is attached to the container body. A first type of closure includes a stamped metal end having an outer edge that is curled for attachment to one end of the container body, and having a relatively large central opening that is closed by a self-adhesive plastic film adhered to the lower surface of the metal end. The plastic film has one or more openings formed by simple X-shaped cuts, such that the openings open with pressure is exerted on the product in the container, allowing a controlled flow of the product out the opening(s). The openings also close automatically when the pressure on the product is ceased. An removable external membrane seal is also attached to the upper surface of the metal end to seal closed the central opening in the metal end until the user is ready to begin using the container, at which time the user removes the membrane seal.
The above-described type of closure has some drawbacks. For instance, the metal end is stamped from sheet metal that is chemically treated to avoid oxidation, and this treatment includes a layer of varnish to prevent contact between the oxidizable metal of the end and the food product in the container. When the metal end is stamped out to make the central opening, the cut edge exposes the oxidizable metal, and this bare metal edge can come into contact with the food product, which is undesirable. The cut edge also can be sharp and can cause injury to the hand of one using the container. Additionally, in an automated manufacturing process, it can be difficult to precisely position the self-adhesive plastic film on the metal end so that it properly and completely covers the opening in the metal end. Many times, mis-positioning of the film occurs, resulting in an unacceptable container.
Furthermore, the plastic film is thin and hence the four flexible tips or leaves of the film formed by an X-shaped cut do not have sufficient stiffness to form an effective valvular or controlled-flow aperture. The aperture tends to open too easily and quickly when the product is pressurized, and tends to close too slowly when the pressure is released so that the flow of product is not controlled as precisely as desired.
A second type of closure also includes a stamped metal end generally as described above in connection with the first type of closure, and a completely independent piece molded of plastic in the form of a disk. The metal end overlies the plastic disk, and the outer edges of the metal end and plastic disk are together secured to the container body, such as by double-seaming. The plastic disk has one or more X-shaped slits forming controlled-flow apertures. A removable membrane seal is affixed to the upper surface of the metal end to seal closed the opening until the container is to be used, as in the first closure.
This second type of closure has the same drawbacks associated with the metal end as already mentioned for the first type of closure, namely, the cut edge of the metal end is exposed for oxidation and can come into contact with the food product, and the sharp cut edge is a cutting hazard. A further disadvantage of the second type of closure is that it can be difficult to position the metal end and plastic disk simultaneously in the precise position with respect to the container body that is required in order to be properly seamed to the container body. Moreover, because two separate pieces must be manufactured, the cost of the closure is unfavorably impacted. In addition, the metal end and plastic disk together have a combined thickness that is considerable, which detracts from the appearance of the container.